Engine and transmissions typically are controlled to provide a driver with requested operation. This is based in large part upon the driver actuated accelerator (gas) pedal. However, information regarding a driver's intention can also be gathered from actuation of the brake pedal.
For example, driver braking information can be used in transitioning from a positive power train output torque (engine driving the vehicle) to a negative power train output torque (vehicle driving the engine) to reduce potential transmission lash during the transition. In one approach (Da et al., U.S. Pat. No. 6,600,988), the duration of brake actuation is utilized. However, whether the driver is actuating the brake significantly, or only slightly, may represent significantly different situations. For example, if a driver is only slightly actuating the brake, albeit for a long period of time, more power train braking than desired may be provided.
Braking information can also be used to control the transmission shifting. For example, in one example approach (Han et al., U.S. Pat. No. 6,625,535), a determined driver braking intent is utilized to shift the transmission. However, transmission shifting in a transmission with a limited number of gears may have reduced control resolution to provide the driver with expected drivability. Furthermore, the approach described by Han et al. may produce a degraded estimate of braking intent at low vehicle speeds, which may result in undesirable transmission shifting.
The inventors herein have recognized the above-mentioned disadvantages and have developed an alternative approach. Further, the inventors herein have advantageously utilized information regarding the driver's braking in entering and/or controlling a deceleration fuel shut-off mode.